class ActionController::Request
    def relative_url_root
      @@relative_url_root ||= case
        when @env["RAILS_RELATIVE_URL_ROOT"]
          @env["RAILS_RELATIVE_URL_ROOT"]
        when server_software == 'apache'
          @env["SCRIPT_NAME"].to_s.sub(/\/dispatch\.(fcgi|rb|cgi)$/, '')
        else
          ''
      end
    end
end